The present invention relates to roof assemblies and a method of installing a roof assembly to form the roof of a building such as a factory or commercial building.
Normally a building is constructed by installing the foundations and floors, constructing a framework for the walls and roof, and then installing the elements which make up the walls, ceiling and roofing, The plumbing and wiring are usually installed once the shell of the building has been constructed.
Typically, the roof of a building in particular is constructed in situ, that is, above the ground. Constructing anything above ground level adds to the cost of construction.
Where buildings have been required in locations having high construction costs, they have been fabricated in modules that have been transported to the site and assembled in situ thereby considerably reducing the cost of labour required at the site. However, to be transportable such modular buildings have lacked aesthetic appeal and when the high cost of transport is taken into account, have not been competitive in situations where construction labour is readily available.
Because the roof of a building is largely assembled above the ground it usually represents a disproportionately high component of the total cost of construction. There is therefore a considerable economic advantage to be obtained by assembling a roof on the ground and lifting it into position as a unitary structure.
Patent application Ser. No. 22914/77 describes a prefabricated roof structure having an underlying peripheral support to provide rigidity so that the structure can be raised as a unit. The prefabricated structure described includes roof trusses, fasica, guttering and rafters. The structure is supported at a level slightly above the ground while tiling or roof sheeting is applied to the frame. The structure is then raised so that the ceiling and soffits can be readily fitted from ground level. The roof structure may be raised by hydraulic or mechanical jacks or cranes according to circumstances.
The proposal described in patent application Ser. No. 22914/77 suffers from a number of disadvantages. Firstly the roof is so designed that it is necessary to add a peripheral support to provide rigidity. The additional materials and time required to construct the support add to the cost of the structure. Secondly the multi-lift assembly of the structure, adds to the cost and increases the risk of accidents arising especially while the ceiling is being installed. An objective of the present invention is therefore to reduce the cost of constructing and installing building roofs and overcome the problems associated with previous proposals.